1. Field of the Invention
The present invention relates to a granulocyte adsorbing carrier for selectively removing granulocytes from blood and a granulocyte remover employing the granulocyte adsorbing carrier.
2. Description of the Background Art
In relation to a method of separating granulocytes from blood, there have generally been proposed a centrifugal separation method utilizing difference in specific gravity, and a method utilizing a material such as cotton, nylon fiber, polyester fiber or silicone-treated glass wool, for example, for allowing selective adhesion of granulocytes (Japanese Patent Laying-Open Nos. 54-46812 (1979) and 57-11920 (1982), for example).
In the method utilizing difference in specific gravity, however, much labor and a long-time operation are required for separating the granulocytes, while lymphocytes are easy to contaminate. As compared with this method, the method utilizing a material for allowing selective adhesion of granulocytes can conceivably efficiently adsorb the granulocytes in a simple operation. In such a method of selectively adsorbing granulocytes, the surface area of an adsorbent is generally maximized thereby improving adsorbability. Therefore, the adsorbent is mainly prepared from fiber.
However, it is impossible to further selectively adsorb the granulocytes by merely increasing the adsorption area of the adsorbent. In fact, Japanese Patent Publication No. 58-54126 (1983) describes that not only granulocytes but lymphocytes are adsorbed.
As disclosed in Japanese Patent Laying-Open No. 2-193069 (1990), on the other hand, the G-L ratio of a granulocyte number G to a lymphocyte number L in a cancer patient is a host marker, which can conceivably serve as effective means for judging a pathologic change of the patient in clinical treatment. It is also suggested that preferable influence is exerted on cancer treatment when the G-L ratio is reduced by selectively removing granulocytes from the blood of the patient.
The aforementioned Japanese Patent Laying-Open No. 2-193069 (1990) discloses a carrier such as polystyrene, cellulose acetate, nylon, polytrifluoroethylene or polyethylene terephthalate having higher affinity to granulocytes as compared with lymphocytes as a granulocyte adsorbing carrier which can be applied to the aforementioned judgement of a pathologic change of a cancer patient or cancer treatment, and describes that granulocytes can be selectively adsorbed by such a carrier. For the purpose of the aforementioned cancer treatment, however, awaited are a carrier and a granulocyte remover which can further selectively adsorb granulocytes.
While Japanese Patent Laying-Open No. 2-193069 (1990) illustrates polystyrene, cellulose acetate, 6-nylon and polyethylene terephthalate as exemplary samples for forming the granulocyte adsorbing carrier as hereinabove described, this gazette further clarifies that the cellulose acetate exhibits excellent granulocyte adsorbability in particular.
However, it is impossible to mold cellulose acetate without employing a plasticizer. Therefore, the cellulose acetate is generally mixed with a plasticizer, to be molded. The plasticizer which can be employed for the cellulose acetate is prepared from an adipic acid, citric acid, glycerolic, phosphoric acid, phthalic acid, sebacic acid or succinic acid plasticizer.
When the aforementioned plasticizer is mixed with the cellulose acetate for molding the same, however, a problem of toxicity arises since the plasticizer component flows out from the adsorbing carrier as obtained into the blood. Further, dioctyl phthalate, being a generally employed plasticizer which is approved for a medical device such as a blood circuit, cannot be applied to cellulose acetate.
While it is obviously preferable to employ a cellulose acetate carrier as a granulocyte adsorbing carrier for a granulocyte remover which is employed for extracorporeal circulation, there has been provided no granulocyte adsorbing carrier of cellulose acetate containing a plasticizer in an approvable amount.